As of today, Nigel and Bob, the surgeon and patient in the whacky Surgeon Simulator 2013, have been joined by the Medic and the Heavy from Team Fortress 2 as a result of a unique agreement between Valve and the game’s creators, Bossa Studios. The new content is available for free to all current and future owners of the game.

Surgeon Simulator 2013 started its life as the result of a 48-hour coding session at the 2013 Global Game Jam, and has since become a smash-hit on Steam thanks to its quirky mechanics and darkly humourous operating-theatre-gone-bad gameplay. Players must perform operations while hampered by unrealistic (yet hilarious) physics and the constant blood loss of their patient.

If this sort of thing appeals (and who doesn’t like surgery-themed mayhem), be sure to check out any of the millions of Let’s Play videos that hit YouTube shortly after the game went on sale on Steam in April. It’s only $9.99 on Steam, so if you like what you see a hundred ZA bucks (or so, depending on what the exchange rate is doing this minute) will nab you a copy.